Philips TEA1094T-C1, TEA1094AT-C1, TEA1094AM-C1, TEA1094A-C1, TEA1094T-C2 Datasheet

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DATA SH EET

Product speciﬁcation Supersedes data of 1996 Mar 11 File under Integrated Circuits, IC03

1996 Jul 15

INTEGRATED CIRCUITS

TEA1094; TEA1094A

Hands free IC

1996 Jul 15 2

Philips Semiconductors Product speciﬁcation

Hands free IC TEA1094; TEA1094A

FEATURES

• Low power consumption

• Power-down function (TEA1094A only)

• Microphone channel with:

– externally adjustable gain – microphone mute function.

• Loudspeaker channel with: – externally adjustable gain – dynamic limiter to prevent distortion – rail-to-rail output stage for single-ended load drive – logarithmic volume control via linear potentiometer – loudspeaker mute function.

• Duplex controller consisting of: – signal envelope and noise envelope monitors for both

channels with: externally adjustable sensitivity externally adjustable signal envelope time constant externally adjustable noise envelope time constant

– decision logic with:

externally adjustable switch-over timing externally adjustable idle mode timing externally adjustable dial tone detector in

receive channel

– voice switch control with:

adjustable switching range constant sum of gain during switching constant sum of gain at different volume settings.

APPLICATIONS

• Mains, battery or line-powered telephone sets with hands-free/listening-in functions

• Cordless telephones

• Answering machines

• Fax machines.

GENERAL DESCRIPTION

The TEA1094 and TEA1094A are bipolar circuits intended for use in mains, battery or line-powered telephone sets, cordless telephones, answering machines and Fax machines. In conjunction with a member of the TEA106X, TEA111X families of transmission circuits, the devices offer a hands-free function. They incorporate a microphone amplifier, a loudspeaker amplifier and a duplex controller with signal and noise monitors on both channels.

ORDERING INFORMATION

TYPE NUMBER

PACKAGE

NAME DESCRIPTION VERSION

TEA1094 DIP28 plastic dual in-line package; 28 leads (600 mil) SOT117-1 TEA1094A DIP24 plastic dual in-line package; 24 leads (600 mil) SOT101-1 TEA1094T SO28 plastic small outline package; 28 leads; body width 7.5 mm SOT136-1 TEA1094AT SO24 plastic small outline package; 24 leads; body width 7.5 mm SOT137-1 TEA1094AM SSOP24 plastic shrink small outline package; 24 leads; body width 5.3 mm SOT340-1

1996 Jul 15 3

Philips Semiconductors Product speciﬁcation

Hands free IC TEA1094; TEA1094A

QUICK REFERENCE DATA

VBB=5V; V

GND

= 0 V; f = 1 kHz; T

amb

=25°C; MUTET = LOW; PD = LOW (TEA1094A only); RL=50Ω; R

VOL

=0Ω;

measured in test circuit of Fig.12; unless otherwise speciﬁed.

Note

1. Corresponds to 200 mW output power.

SYMBOL PARAMETER CONDITIONS MIN. TYP. MAX. UNIT

supply voltage 3.3 − 12.0 V

current consumption from pin V

− 3.1 4.4 mA

vtx

voltage gain from pin MIC to pin MOUT in transmit mode

MIC

= 1 mV (RMS);

GAT

= 30.1 kΩ

13 15.5 18 dB

∆G

vtxr

voltage gain adjustment with R

GAT

−15.5 − +15.5 dB

vrx

voltage gain in receive mode; the difference between RIN1 and RIN2 to LSP

RIN

= 20 mV (RMS);

GAR

= 66.5 kΩ;

RL=50Ω

16 18.5 21 dB

∆G

vrxr

voltage gain adjustment with R

GAR

−18.5 − +14.5 dB

O(p-p)

output voltage (peak-to-peak value) V

RIN

= 150 mV (RMS);

GAR

= 374 kΩ; RL=33Ω; VBB= 9.0 V; note 1

− 7.5 − V

SWRA switching range − 40 − dB ∆SWRA switching range adjustment with R

SWR

referenced to R

SWR

= 365 kΩ

−40 − +12 dB

amb

operating ambient temperature −25 − +75 °C

1996 Jul 15 4

Philips Semiconductors Product speciﬁcation

Hands free IC TEA1094; TEA1094A

BLOCK DIAGRAM

Fig.1 Block diagram.

handbook, full pagewidth

MGE436

LOG

BUFF

LOG

BUFF

LOGIC

V I

I V

VOICE

SWITCH

DYNAMIC

LIMITER

VOLUME

CONTROL

I V

V I

DLC/MUTER

LSP

GAR

RSEN

RENV

RNOI

TNOI

TENV

TSEN

MIC

MUTET

VOL

RIN2

RIN1

SWR

STAB

SWT

IDT

MICGND

MOUT

GAT

GND

(1)

10 (7)

(13)

(15)

(18)

(24)

(23)

(22)

(19)

(20)

(21)

(4)

(5)

(1)

(6)

(17)

(16)

(14)

(12)

(11)

(10)

(9)

(2)

(3)

11 (8)

13 mV

ATTENUATOR

13 mV

ref

MIC

TSEN

TENV

TNOI

RNOI

RENV

RSEN

GAR

LSP

DLC

GAT

to TEA106x

IDT

SWT

STAB

SWR

from

TEA106x

VOL

LOUDSPEAKER CHANNEL

DUPLEX

CONTROLLER

MICROPHONE CHANNEL

TEA1094

TEA1094A

The pin numbers given in parenthesis are for the TEA1094A. (1) TEA1094A only.

1996 Jul 15 5

Philips Semiconductors Product speciﬁcation

Hands free IC TEA1094; TEA1094A

PINNING

SYMBOL

PINS

DESCRIPTION

TEA1094 TEA1094A

DLC/

MUTER 1 1 dynamic limiter timing adjustment; receiver channel mute input RIN1 2 2 receiver ampliﬁer input 1 RIN2 3 3 receiver ampliﬁer input 2 n.c. 4 − not connected GAR 5 4 receiver gain adjustment LSP 6 5 loudspeaker ampliﬁer output n.c. 7 − not connected GND 8 6 ground reference n.c. 9 − not connected V

10 7 supply voltage VOL 11 8 receiver volume adjustment SWR 12 9 switching range adjustment STAB 13 10 reference current adjustment SWT 14 11 switch-over timing adjustment n.c. 15 − not connected IDT 16 12 idle mode timing adjustment PD − 13 power-down input n.c. 17 − not connected MICGND 18 14 ground reference for the microphone ampliﬁer MUTET 19 15 transmit channel mute input MOUT 20 16 microphone ampliﬁer output GAT 21 17 microphone gain adjustment MIC 22 18 microphone input RNOI 23 19 receive noise envelope timing adjustment RENV 24 20 receive signal envelope timing adjustment RSEN 25 21 receive signal envelope sensitivity adjustment TNOI 26 22 transmit noise envelope timing adjustment TENV 27 23 transmit signal envelope timing adjustment TSEN 28 24 transmit signal envelope sensitivity adjustment

1996 Jul 15 6

Philips Semiconductors Product speciﬁcation

Hands free IC TEA1094; TEA1094A

Fig.2 Pin configuration (TEA1094).

handbook, halfpage

DLC/MUTER

RIN1 RIN2

n.c.

GAR

LSP

n.c.

GND

n.c.

VOL

SWR

STAB

SWT

TSEN TENV TNOI RSEN

RNOI MIC

RENV

GAT MOUT MUTET MICGND n.c. IDT n.c.

1 2 3 4 5 6 7 8

9 10 11 12 13

28 27 26 25 24 23 22 21 20 19 18 17 16 1514

TEA1094

MGE434

Fig.3 Pin configuration (TEA1094A).

handbook, halfpage

DLC/MUTER

RIN1 RIN2

GAR

LSP

GND

VOL

SWR

STAB

SWT

IDT

TSEN TENV TNOI RSEN

RNOI MIC

RENV

GAT MOUT MUTET MICGND PD

1 2 3 4 5 6 7 8

9 10 11 12

24 23 22 21 20 19 18 17

16 15 14 13

TEA1094A

MGE435

FUNCTIONAL DESCRIPTION General

The values given in the functional description are typical values unless otherwise specified.

A principle diagram of the TEA106X is shown on the left side of Fig.4. The TEA106X is a transmission circuit of the TEA1060 family intended for hand-set operation. It incorporates a receiving amplifier for the earpiece, a transmit amplifier for the microphone and a hybrid. For more details on the TEA1060 family, please refer to

“data Handbook IC03”

. The right side of Fig.4 shows a principle diagram of the TEA1094 and TEA1094A, hands-free add-on circuits with a microphone amplifier, a loudspeaker amplifier and a duplex controller.

As can be seen from Fig.4, a loop is formed via the sidetone network in the transmission circuit and the acoustic coupling between loudspeaker and microphone of the hands-free circuit. When this loop gain is greater than 1, howling is introduced. In a full duplex application, this would be the case. The loop-gain has to be much lower than 1 and therefore

has to be decreased to avoid howling. This is achieved by the duplex controller. The duplex controller of the TEA1094 and TEA1094A detects which channel has the ‘largest’ signal and then controls the gain of the microphone amplifier and the loudspeaker amplifier so that the sum of the gains remains constant. As a result, the circuit can be in three stable modes:

1. Transmit mode (Tx mode). The gain of the microphone amplifier is at its maximum

and the gain of the loudspeaker amplifier is at its minimum.

2. Receive mode (Rx mode). The gain of the loudspeaker amplifier is at its

maximum and the gain of the microphone amplifier is at its minimum.

3. Idle mode. The gain of the amplifiers is halfway between their

maximum and minimum value.

The difference between the maximum gain and minimum gain is called the switching range.

1996 Jul 15 7

Philips Semiconductors Product speciﬁcation

Hands free IC TEA1094; TEA1094A

Fig.4 Hands-free telephone set principles.

handbook, full pagewidth

MGE438

DUPLEX

CONTROL

HYBRID

telephone

line

sidetone

acoustic coupling

TEA106x

TEA1094

TEA1094A

Supply: pins VBB, GND and PD

The TEA1094 and TEA1094A must be supplied with an external stabilized voltage source between pins V

and GND. In the idle mode, without any signal, the internal supply current is 3.1 mA at VBB=5V.

To reduce the current consumption during pulse dialling or register recall (flash), the TEA1094A is provided with a power-down (PD) input. When the voltage on PD is HIGH the current consumption from VBB is 180 µA.

Microphone channel: pins MIC, GAT, MOUT, MICGND and MUTET (see Fig.5)

The TEA1094 and TEA1094A have an asymmetrical microphone input MIC with an input resistance of 20 kΩ. The gain of the input stage varies according to the mode of the TEA1094 and TEA1094A. In the transmit mode, the gain is at its maximum; in the receive mode, it is at its minimum and in the idle mode, it is halfway between maximum and minimum.

Switch-over from one mode to the other is smooth and click-free. The output capability at pin MOUT is 20 µA (RMS).

In the transmit mode, the overall gain of the microphone amplifier (from pins MIC to MOUT) can be adjusted from 0 dB up to 31 dB to suit specific application requirements. The gain is proportional to the value of R

GAT

and equals

15.5 dB with R

GAT

= 30.1 kΩ.

A capacitor must be connected in parallel with R

GAT

to ensure stability of the microphone amplifier. Together with R

GAT

, it also provides a first-order low-pass filter.

By applying a HIGH level on pin MUTET, the microphone amplifier is muted and the TEA1094 and TEA1094A are automatically forced into the receive mode.

1996 Jul 15 8

Philips Semiconductors Product speciﬁcation

Hands free IC TEA1094; TEA1094A

Fig.5 Microphone channel.

handbook, full pagewidth

MGD343

V I I V

MIC

MUTET

MIC

from voice switch

envelope

detector

MICGND

MOUT

GAT 21

(17)

(15)

(18)

(16)

(14)

to TEA106X

GAT

logic

The pin numbers given in parenthesis refer to the TEA1094A.

Loudspeaker channel

Fig.6 Loudspeaker channel.

handbook, full pagewidth

MGE437

DYNAMIC

LIMITER

VOLUME

CONTROL

I V

V I

DLC/MUTER

LSP

GAR

VOL

RIN2

RIN1

(4)

(5)

(1)

(2) 3

(3)

11 (8)

GAR

LSP

DLC

from

TEA106x

VOL

logic

to/from

voice switch

envelope

detector

The pin numbers given in parenthesis refer to the TEA1094A.

1996 Jul 15 9

Philips Semiconductors Product speciﬁcation

Hands free IC TEA1094; TEA1094A

LOUDSPEAKER AMPLIFIER: PINS RIN1, RIN2, GAR AND LSP The TEA1094 and TEA1094A have symmetrical inputs for

the loudspeaker amplifier with an input resistance of 40 kΩ between RIN1 and RIN2 (2 × 20 kΩ). The input stage can accommodate signals up to 390 mV (RMS) at room temperature for 2% of total harmonic distortion (THD). The gain of the input stage varies according to the mode of the TEA1094 and TEA1094A. In the receive mode, the gain is at its maximum; in the transmit mode, it is at its minimum and in the idle mode, it is halfway between maximum and minimum. Switch-over from one mode to the other is smooth and click-free. The rail-to-rail output stage is designed to power a loudspeaker connected as a single-ended load (between LSP and GND).

In the receive mode, the overall gain of the loudspeaker amplifier can be adjusted from 0 dB up to 33 dB to suit specific application requirements. The gain from RIN1 and RIN2 to LSP is proportional to the value of R

GAR

and equals 18.5 dB with R

GAR

= 66.5 kΩ. A capacitor

connected in parallel with R

GAR

can be used to provide a

first-order low-pass filter.

OLUME CONTROL: PIN VOL

The loudspeaker amplifier gain can be adjusted with the potentiometer R

VOL

. A linear potentiometer can be used to obtain logarithmic control of the gain at the loudspeaker amplifier. Each 950 Ω increase of R

VOL

results in a gain loss of 3 dB. The maximum gain reduction with the volume control is internally limited to the switching range.

YNAMIC LIMITER: PIN DLC/MUTER

The dynamic limiter of the TEA1094 and TEA1094A prevents clipping of the loudspeaker output stage and protects the operation of the circuit when the supply voltage at VBB falls below 2.9 V.

Hard clipping of the loudspeaker output stage is prevented by rapidly reducing the gain when the output stage starts to saturate. The time in which gain reduction is effected (clipping attack time) is approximately a few milliseconds. The circuit stays in the reduced gain mode until the peaks of the loudspeaker signals no longer cause saturation. The gain of the loudspeaker amplifier then returns to its normal value within the clipping release time (typically 250 ms). Both attack and release times are proportional to the value of the capacitor C

DLC

. The total harmonic distortion of the loudspeaker output stage, in reduced gain mode, stays below 5% up to 10 dB (minimum) of input voltage overdrive [providing V

RIN

is below 390 mV (RMS)].

When the supply voltage drops below an internal threshold voltage of 2.9 V, the gain of the loudspeaker amplifier is rapidly reduced (approximately 1 ms). When the supply voltage exceeds 2.9 V, the gain of the loudspeaker amplifier is increased again.

By forcing a level lower than 0.2 V on pin DLC/

MUTER, the loudspeaker amplifier is muted and the TEA1094 (TEA1094A) is automatically forced into the transmit mode.

Duplex controller

IGNAL AND NOISE ENVELOPE DETECTORS: PINS TSEN,

TENV, TNOI, RSEN, RENV

AND RNOI

The signal envelopes are used to monitor the signal level strength in both channels. The noise envelopes are used to monitor background noise in both channels. The signal and noise envelopes provide inputs for the decision logic. The signal and noise envelope detectors are shown in Fig.7.

For the transmit channel, the input signal at MIC is 40 dB amplified to TSEN. For the receive channel, the differential signal between RIN1 and RIN2 is 0 dB amplified to RSEN. The signals from TSEN and RSEN are logarithmically compressed and buffered to TENV and RENV respectively. The sensitivity of the envelope detectors is set with R

TSEN

and R

RSEN

. The capacitors connected in series with the two resistors block any DC component and form a first-order high-pass filter. In the basic application, see Fig.13, it is assumed that V

MIC

= 1 mV (RMS) and

RIN

= 100 mV (RMS) nominal and both R

TSEN

and R

RSEN

have a value of 10 kΩ. With the value of C

TSEN

and C

RSEN

at 100 nF, the cut-off frequency is at 160 Hz. The buffer amplifiers leading the compressed signals to

TENV and RENV have a maximum source current of 120 µA and a maximum sink current of 1 µA. Together with the capacitor C

TENV

and C

RENV

, the timing of the signal envelope monitors can be set. In the basic application, the value of both capacitors is 470 nF. Because of the logarithmic compression, each 6 dB signal increase means 18 mV increase of the voltage on the envelopes TENV or RENV at room temperature. Thus, timings can be expressed in dB/ms. At room temperature, the 120 µA sourced current corresponds to a maximum rise-slope of the signal envelope of 85 dB/ms. This is sufficient to track normal speech signals. The 1 µA current sunk by TENV or RENV corresponds to a maximum fall-slope of 0.7 dB/ms. This is sufficient for a smooth envelope and also eliminates the effect of echoes on switching behaviour.

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